* {
    box-sizing: border-box;
}
body {
    margin: 0;
    padding: 0;
    font-family: 'Montserrat', sans-serif;
}
.container {
    display: flex;
    height: 100vh;
    /*flex-flow: column;*/
}
.section {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
    overflow: hidden;
    background-size: cover;
    background-position: center;
    color: #fff;
    transition: flex .4s ease;
    position: relative;
}
.section .overlay {
    background-color: rgba(0, 0, 0, 0.7);
    width: 100%;
    height: 100%;
    position: absolute;
    transition: background-color .8s ease;
}
.section .content {
    z-index: 2;
}
.section:hover {
    flex: 2;
}
.section:hover .overlay {
    background-color: rgba(0, 0, 0, 0.95);
}
#marketing {
    background-image: url(../img/paoche2.jpeg);
}
#technology {
    background-image: url(../img/senlinlang.jpg);
}
#advertising {
    background-image: url(../img/good16.jpg);
}